1. Field of the Invention
The present invention relates to a tubing expansion tool. In particular, but not exclusively, the present invention relates to a tubing expansion tool including an expansion member which is radially moveable.
2. Description of the Related Art
A number of different tools have been proposed for carrying out expansion of downhole tubing such as expandable bore-lining tubing. The applicant's International Patent Publication No. WO 00/37766 discloses a rotary expansion tool including a number of rollers mounted on radially moveable pistons. Fluid pressure urges the pistons radially outwardly, to bring the rollers into contact with tubing to be expanded. The tool is then rotated and advanced axially through the tubing to expand the tubing to a greater internal diameter.
The rollers are compliant such that if the tool encounters a portion of tubing which cannot be expanded, the rollers can move inwardly to advance through the restriction.
However, although offering numerous advantages, use of a tool with compliant rollers introduces the possibility of the occurrence of irregularities in the internal diameter of the expanded tubing, which may not be appropriate. For example, if it is desired to hang an expandable liner from borehole casing, a portion of the upper end of the liner may be expanded into contact with the casing to provide hanging support for the liner, with another portion of the liner being expanded into contact with the casing to provide a fluid seal between the liner and the casing. Thus, the liner must be expanded to a determined outer diameter; if a compliant tool has been utilised, it cannot be determined that the liner has been expanded to the appropriate diameter.